The present invention is related to synthesis of a novel series of phenolic phosphite compounds, and their use as an antioxidant for a polymer.
The oxidation reaction is present in every stage of the life cycle of the polymer such as synthesis, processing and final application. There are several different approaches to reduce the speed of or prevent the oxidation reaction and addition of antioxidants seems to be the most convenient way to retard the oxidation reaction. Hindered phenols, used as processing and long-term stabilizers, are the most favored type of primary antioxidants for thermoplastics, while organic phosphites are used as efficient processing stabilizers for polyolefin protection on a wide commercial scale. Traditionally, the combination of radical scavenger (hindered phenols) with hydroperoxide decomposer (organophosphites) has been widely used by the polymer industry to provide a powerful synergism for the protection of polymers.
Low molecular weight hindered phenol can be easily removed from the polymer by migration and volatilization, while these can be reduced for the large enough molar mass.
U.S. Pat. Nos. 4,474,917 and 4,526,918 disclose a large molar mass phenolic phosphite antioxidant prepared by forming a sodium salt of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and reacting a phosphorus trihalide, preferably PCl3, with the heated sodium salt. The price of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxbenzyl)benzene and the use of NaH for forming the sodium salt render this prior art antioxidant less competitive in the market.
A primary objective of the present invention is to provide a novel series of phenolic phosphite compounds.
Another objective of the present invention is to provide a polymer composition comprising a phenolic phosphite compound as an antioxidant.
A further objective of the present invention is to provide a method for synthesizing a novel series of phenolic phosphite compounds.
In order to accomplish the aforesaid objectives a novel series of phenolic phosphite compounds having the following formula (I), (II) or (III): 
wherein Q is 
Preferably, the phenolic phosphite compounds of the present invention have a structure of the formula (I).
Preferably, the phenolic phosphite compounds of the present invention have a structure of the formula (II).
Preferably, the phenolic phosphite compounds of the present invention have a structure of the formula (III).
The present invention also provides a polymer composition comprising a polymer and 0.01-5% of a phenolic phosphite compound having a formula (I), (II) or (III) as an antioxidant, based on the weight of the polymer.
The phenolic phosphite compounds of the present invention have advantages of both the hindered phenol and the phosphite antioxidants, and a relatively easier synthesis procedures, and thus a lower production cost.